Shelf construction for a multistage dryer for bodies in plate or sheet form



d- 7 1957 A. E. MAKINEN 3,346,967

SHELF CONSTRUCTION FOR A MULTISTAGE DRYER FOR BODIES IN PLATE OR SHEET FORM Filed Oct. 20, 1964 2 Sheets-Sheet 1 Oct. 17, 1967 A. E. MAKINEN 3,346,967

SHELF CONSTRUCTION FOR A MULTISTAGE DRYER FOR BODIES IN PLATE OR SHEET FORM Filed Oct. 20, 1964 2 sheets-sheet 2 a U\ l I NVENTOR ALI- 0 [IA/0 MA'lK/NEA/ United States Patent Ofi ice ABSTRACT OF THE DISCLOSURE Adrying apparatus for drying sheets of pervious mate rial such as veneer sheets. The drying apparatus comprises a plurality of shelves each corrugated to form alternate crests and troughs, first channels located between the troughs opening to a supply duct for drying medium on one side of the apparatus and second channels located between the crests opening to a discharge duct on the other side of the apparatus, the crests of each shelf being arranged'to support-a sheet to be dried. Theapparatus further comprises closure means in each second channel adjacent said one side to prevent drying medium entering the second channels directly when the apparatus is stacked with sheets, and an arrangement on the other side of the apparatus for preventing drying medium entering the discharge d-uct directly from the first channels when the apparatus is stacked with sheets.

This invention relates to a shelf construction in a mu1tistage dryer for bodies in plate or sheet form, for instance veneer sheets, and the object'of the invention is to provide a simple shelf construction which requires a minimum of space. 1

Multistage dryers in" which the drying medium is' desired to be led through the pores of the sheet generally are provided with 'a' screen or similar base, permeable to thedrying'medium,- for the plate .or sheet to be dn'ed, and at each side' of said base, with partitions of a material impermeable to the drying medium, in spaced'relation to :saidba'se, separating the various shelves or layersfrom each other. v

According to the present invention a separate support base can-be totally omitted, since the shelves are made of sheet material to form alternately upwardly and downwardly directed crest's', p referablyrunning in the cross direction of the shelf, and the invention is essentially characterized in that the channels between the upwardly directed crests are closed in one end, and, at least in the middle portion of the shelf construction, open in the other end to the collection channel of the drying medium being discharged, and that the channels for the drying medium feed between the downwardly directed crests are closed towards the collection channel of the discharging drying medium so as to compel the drying medium to pass through the plate or sheet to be dried.

A preferred shelf construction according to the invention consists of corrugated plate or the like, but the profile, of course, can be of any desired formation. The sheet to be dried is supported on the upwardly directed crests on such shelf, and the drying medium is supplied to the upper side of the sheet to be dried, between the downwardly directed crests of the upper shelf, and, preferably having passed through the sheet, discharges between the crests on which the sheet is supported. The passage of the drying medium through the sheet is accomplished either by means of pressure above the sheet or by means of a suction effect below the sheet. This arrangement allows free shrinkage of the sheet during drying, which in turn results in a material saving during the sheet cutting operation, bearing in mind that the sheets can be dried in the form of continuous webs.

Patented Oct. 17, 1967 At the ends of the shelves a certain number of the openings of the discharge channels between the upwardly directed crests, facing the collection channel of the discharging drying medium, are preferably provided with closing devices which automatically close whenever no sheet to be dried is present at the point, or in case the sheet when drying shrinks enough to make the sheet recede from above the respective discharge channel. This prevents the drying medium from discharging inetfectively from between the drying shelves. There can be ten of these automatically closing channels, for instance, at each end of the shelf. In the following the invention will be described in more detail with reference to the accompanying drawings, in which ashelf construction according to the invention is shown by way of example' In the drawings:

FIG. 1 shows an end elevation of the shelf construction according to the invention viewed from the side of the multistage dryer, 7

FIG. 2 is an elevational view of the device by which the discharge channels between the upwardly directed crests ,can be totallyclosed at the drying medium feed side, and of the flap device at the discharge side opening and closing automatically, said device being shown mounted in a drying medium feeding channel,

'FIG. 3 shows the, stationary closure damper of the 'device shown in FIG. 2 viewed from the front side from vertical section line AA of FIG. 2,

FIG. 4 shows the automatically operated flap likewise viewed from the front sidefrom vertical section line B-B ofFIG.2, f

FIG. Srshows one. of, the upwardly directed crests in greater scale viewed ,from'the 'feed'side of the dryer,

FIG. 6 is a cross section of the feed end of the crest of FIG. 5 with guide strips for the sheet in greater scale viewed inthe longitudinal direction of the dryer,

- FIG. 7 is a somewhat schematioview in longitudinal vertical section through three shelves of a drying apparatus embodying theinvention,

FIG. 8 is a view in vertical transverse section through a shelf in accordance with the present invention, a sheet 'of material being shown in the act, of being introduced onto the shelf, and '1 FIG. 9 is aview similar to'FIG. 8 butlwith the sheet of material shown resting upon the shelf while it is being dried.

In the drawings the upwardly directed crests are indicated at 1 and the discharge channels formed between the crests are indicated at 2, while the downwardly directed crests and the supply channels for the drying medium formed therebetween are indicated at 3 and 4 respectively. The ends 5 facing towards the feed side of the dryer, of the upwardly directed crests 1 are preferably somewhat bevelled, and in the construction according to the draw ing an inclined strip 6 extending over the whole length of the dryer is attached to the downwardly directed crests 3. The inclined planes 5 and 6 thus formed facilitate the feeding in of the veneer sheets between the respective shelves of the multistage dryer.

As the sheets coming from a veneer sheet forming lathe notoriously are not uniform in dimension and as the sheet beside-s always shrinks during drying, a number of discharge channels at the end of the corrugated plate shelf would be open and the drying medium could freely escape therethrough. To eliminate this defect there is provided the device shown in FIGURES 2-4, by means of which these channels 2 are closed whenever the veneer sheet does not cover the same.

The device mentioned above consists of a rod 7, having a plate 8 attached for instance by welding to the end thereof facing the feed side of the multistage dryer, which plate thus closes this end of the channel 2. To the opposite 3 end of the rod is attached a transverse support 9, which also supports the rod 7 by resting on the crests 1; the upper end of support 9 is bent in the direction of the rod and again bent a little upwards, forming a stop face, against which the sheet stops. The support 9 is provided with a flap 11, hinged to its lower edge, to which flap a forked lever arm 12 is attached, which arm, any time the sheet rests against it, is pressed down and thus opens the flap 11. As the sheet shrinks when driyng the recedes from above the lever 12, the flap 11 ,falls down and closes the discharge end of the discharge channel 2, thus preventing the drying medium from escaping therethrough to a collection channel 14 with which it is associated, as shown in FIGS. 8 and 9. In the middle portion of the shelf construction, where the flap 11 is not needed, the plate 8 is attached directly to the end of the channel 2 that points towards the feed end of the dryer. For servicing and maintenance the flap device can easily be removed by means of the rod 7. In actual operation a pressure difference of 7 mm. Hg has been observed be tween the group formed by the channels 4and the discharge channel -2. The fact that a certain amount of drying medium manages to escape at the edges of the sheet to the channels 2 does not essentially affect the drying result.

The invention is by no means limited to the construction described above and it can be varied and modified in many ways within the scope of the attached claims. Thus the profile of the crests and the channels therebetween can have practically any formation, and the mechanism of the flap device can be other than described above. The main thing isto have that discharge channel 2 closed, above which there is no sheet at the moment.

What I claim is:

1. A shelf construction for a multistage dryer used for drying pervious bodies such as veneer sheets in plate or sheet form, the shelf being made of sheet material and corrugated to form parallel crests directed alternately upwardly and. downwardly, the body being dn'ed resting upon the upwardly directed crests of the shelf, there being an upwardly open channel between successive upwardly directed crests and a downwardly open channel between successive downwardly directed crests, and means extending transversely of the upwardly open channels at a first end thereof for closing the channels at said first end thereof, said upwardly open channels being open in at least the middle portion so as directly to communicate with the lower face of the pervious body which overlies such channels, the second end of each upwardly open channel being adapted to be connected to a collection channel, whereby drying medium fed to the shelf from above a sheet of material resting upon the upwardly directed crests of the shelf passes through the pervious material into the upwardly directed channels of the shelf and thence to the collection channel connected thereto.

'2. A shelf construction as claimed in claim 1, comprising means in at least some of the upwardly open channels adjacent the second ends thereof for closing the up-' wardly open channels to prevent the direct passage of the drying medium therefrom into the collection channel, said channel-closing means including means responsive to the presence of a portion of the sheet material being dried upon the zone of the shelf in the vicinity of the closure means, such last named means being so constructed and arranged as automatically to close the closure means whenever no portion of the material being dried is present at such zone and to open the closure means when a portion of the material being dried is present at such zone.

3. A shelf construction as claimed in claim 2, wherein the channel-closing means consists of a transverse flap pivotally mounted on the shelf so that it may be swung from a generally vertical position in which it spans and closes the upwardly open channel with which it is associated to a generally horizontal position in which it lies above the upwardly open channel so as to open such channel to the collection channel, the means responsive to the presence upon said zone of the shelf of a portion of the material being dried comprising a lever connected to the flap and extending generally vertically above the up wardly directed crests of the shelf when the flap is in its vertical, channel-closing position, engagement between a the material being dried and the lever pivoting the flap into its open position.

References Cited,

MARTIN P. SCHWADRON, Primary Examiner.

C HE si tant E min 

1. A SHELF CONSTRUCTION FOR A MULTISTAGE DRYER USED FOR DRYING PERVIOUS BODIES SUCH AS VENEER SHEETS IN PLATE OR SHEET FORM, THE SHELF BEING MAED OF SHEET MATERIAL AND CORRUGATED TO FORM PARALLEL CRESTS DIRECTED ALTERNATELY UPWARDLY AND DOWNWARDLY, THE BODY BEING DRIED RESTING UPON THE UPWARDLY DIRECTED CRESTS OF THE SHELF, THERE BEING AN UPWARDLY OPEN CHANNEL BETWEEN SUCCESSIVE UPWARDLY DIRECTED CRESTS AND A DOWNWARDLY OPEN CHANNEL BETWEEN SUCCESSIVE DOWNWARDLY DIRECTED CRESTS, AND MEANS EXTENDING TRANSVERSELY OF THE UPWARDLY OPEN CHANNELS AT A FIRST END THEREOF FOR CLOSING THE CHANNELS AT SAID FIRST END THEREOF, SAID UPWARDLY OPEN CHANNELS BEING OPEN IN AT LEAST THE MIDDLE PORTION SO AS DIRECTLY TO COMMUNICATE WITH THE LOWER FACE OF THE PERVIOUS BODY WHICH OVERLIES SUCH CHANNELS, THE SECOND END OF EACH UPWARDLY OPEN CHANNEL BEING ADAPTED TO BE CONNECTED TO A COLLECTION CHANNEL, WHEREBY DRYING MEDIUM FED TO THE SHELF FROM ABOVE A SHEET OF MATERIAL RESTING UPON THE UPWARDLY DIRECTED CRESTS OF THE SHELF PASSES THROUGH THE PERVIOUS MATERIAL INTO THE UPWARDLY DIRECTED CHANNELS OF THE SHELF AND THENCE TO THE COLLECTION CHANNEL CONNECTED THERETO. 